1. Field of the Invention
This invention relates to a method of preventing asphalt from sticking to paving equipment, utilizing a device that will apply a release coating to paving equipment surfaces, said coating is a diluted mixture of a viscous concentrate, and said coating is a viscous solution. The method comprises:
1) coating a paving equipment surface by spraying, rolling or brushing with a release agent,
2) adding or contacting tar or asphalt to the equipment or otherwise handling or using the asphalt with the sprayed equipment, and
3) separating the asphalt from the equipment by releasing it at its point of intended use or
4) otherwise releasing the tar or asphalt from the paving equipment.
The method utilizes a piece of equipment that makes it possible to spray on highly-viscous dilutions of highly-active asphalt release agents. The device consists essentially of:
1) a carbonator pump or other vaned, positive-displacement pump which produces a minimum flow of about one gallon per minute (xe2x80x9c1 GPMxe2x80x9d) and 200-300 pounds per square inch (xe2x80x9cpsixe2x80x9d) pressure; and associated electric motor to drive the pump,
2) a timer relay to control the pump and motor,
3) an induction/injection valve with a high induction capacity resulting in a dilution ratio of to concentrate as low as about a 10/1 dilution ratio, even with viscous concentrates,
4) a spray gun with an appropriately-sized nozzle, (or a spray bar and a multiplicity of nozzles) and
5) necessary tubing, fittings, connections, control buttons, a box to enclose the apparatus, as well as a pressure relief valve and/or bypass valve, freeze protection, a particulate-filtering screen or screens, a solenoid to prevent non-pumped release of the release coating as optional ancillary devices.
The singular advantages of the instant invention are that the system utilizes only one pump, the components are very durable, so the system is therefore robust, and the system is able to deliver effective sprays of highly-viscous release coatings, in the right and adjustable dilution ratio, and from viscous concentrates.
2. Prior Art
2.1. General Considerations
It is well-known in the industry that tar and asphalt, used in their molten or liquid state, have a strong tendency to adhere to surfaces of the equipment used to handle, transport and otherwise use them. This buildup can be severe, rendering the equipment completely unsuitable for its purpose.
One traditional way to address this problem has been to spray the equipment with diesel fuel, which forms a lubricating layer in between the asphalt and the equipment. However, for regulatory and other reasons, this has become an obsolete method.
2.2. Examples of Prior and/or Related Art
One response to the regulatory pressure to stop using diesel fuel has been to use other, less environmentally-unacceptable alternative solvents. An example of this type is xe2x80x9c004xe2x80x9d, a citrus-based solvent sold by the Zep Company. It is used to clean paving equipment and to prevent tar or asphalt from sticking to the equipment in the first place. This type of solvent suffers from several drawbacks, at least one of which is the increased cost compared to diesel fuel.
Another drawback to this approach is that frequently the solvents chosen have a detrimental effect on the asphalt or tar in its final location, leading to a decreased strength of the resultant surface. For this reason, most such solvents can not be approved by state departments of transportation (DOT) for use as truck bed release agents, and so cannot be used on truck beds that are carrying asphalt to pave on state roads.
Typically, the tests are rather severe, for instance allowing contact between asphalt and solvent for 24 hours, and determining if there is any discoloration whatsoever in the solvent mixture. Most solvents used for release agents are unable to pass such a test.
Another response has been to utilize water-dilutable formulations. The major solvent in this situation is water, which is cheap and plentiful, and known to repel asphalt. However, many of these materials suffer from serious drawbacks, leading to a reputation in the industry that they are ineffective. The major drawback with such poorly-performing formulations is that they are mostly water to begin with, and the resultant highly-dilute water film is insufficiently persistent.
Other water-dilutable formulations, such as LiquiSlip by the Dubois Corporation utilize a combination of these two methods. The concentrate contains a petroleum solvent and emulsifiers, and a special machine combines the concentrate with water to form a creamy emulsion, which the apparatus sprays on the surfaces to be release coated, and the coating acts to prevent asphalt from sticking. The major problems associated with this approach are that it involves petroleum-based solvents, and that two pumps and a specialized delivery system are required to make it work.
The petroleum solvent in the product makes it unacceptable to accidentally spray it on the ground. The emulsified product is highly-viscous when diluted, and so spraying it requires two pumps, one to pump the concentrate, and another to pump the diluted mixture. This approach can be undesirable, moreover, due to the increased costs associated with utilizing two pumps, both in terms of initial capital, and in terms of difficulty, frequence and cost of maintenance, balancing the outputs of the two pumps, etc.
A formulation recently patented by Chemtek, Inc., is the subject of U.S. Pat. No. 6,126,757. This formulation comprises primarily fatty acids neutralized by organic nitrogenous bases, and fatty acid amides. The formulation is rather viscous, and the resulting dilutions are very viscous.
No device currently known to be on the market is able to adequately and inexpensively deliver dilutions of these formulations, and so a special device was required. It is the object of this invention to provide such a device, to be able to utilize the above-mentioned formulation. This device utilizes only one pump, and so minimizes the expense and difficulty associated with the products"" delivery.
An object of the present invention is to provide a method to prevent tar or asphalt from sticking to paving equipment, but without resorting to using solvents that may attack the asphalt. Another object of the present invention is to provide a method of utilizing water as a diluent, a cheap, plentiful diluent that also repels asphalt. It is another object of the present invention to provide a method to protect equipment from getting tar or asphalt stuck to them without resort to petroleum-based, natural-origin or chlorine-containing solvents.
These and other objects of the present invention have been attained by the present inventors"" discovery of a method for preventing asphalt and tar from sticking to paving equipment, comprising contacting the surfaces with a dilution of a concentrated solution by spraying the diluted concentrate on the equipment prior to contacting the equipment with asphalt or tar, said spraying equipment to include, but not be limited to:
1) a carbonator pump or other vaned, positive-displacement pump which produces a minimum flow of about one gallon per minute (xe2x80x9c1 GPMxe2x80x9d) and 200-300 pounds per square inch (xe2x80x9cpsixe2x80x9d) pressure; and associated electric motor to drive the pump,
2) a timer relay to control the pump and motor,
3) an induction/injection valve with a high induction capacity of as low as about a 10/1 dilution ratio, even with viscous concentrates,
4) a spray gun with an appropriately-sized nozzle, (or a spray bar and a multiplicity of nozzles) and
5) necessary tubing, fittings, connections, control buttons, a box to enclose the apparatus, as well as a pressure relief valve and/or bypass valve, freeze protection, a particulate-filtering screen or screens, a solenoid to prevent non-pumped release of the release coating as optional ancillary devices.
This invention relates to a method of preventing tar and asphalt from sticking to paving equipment. The method comprises coating a paving equipment surface by spraying it with a release agent, 2) adding or contacting tar or asphalt to the equipment or otherwise handling or using the asphalt, and 3) if transportation or movement of the asphalt or tar is the desired purpose of utilizing the paving equipment, separating the asphalt from the equipment by releasing it at its point of intended use or otherwise releasing the asphalt or tar or related material from the paving equipment.
More particularly, the invention relates to utilizing a device to automate the water dilution of a concentrate, preferably comprising a fatty acid amide or mixture of fatty acid amides, a fatty acid neutralized with an alkanolamine, and optionally a solvent or solvents, of a type(s) that does (do) not dissolve asphalt. However, other types of concentrates could conceivably be used with the instant invention, a method which utilizes the following components:
1) a carbonator pump or other graphite-vaned, positive-displacement pump which produces a minimum flow of about one gallon per minute (xe2x80x9c1 GPMxe2x80x9d) and 250-300 pounds per square inch (xe2x80x9cpsixe2x80x9d) pressure; and associated electric motor to drive the pump,
2) a timer relay to control the pump and motor,
3) an induction/injection valve with a high induction capacity of as low as about a 10/1 dilution ratio, even when pumping viscous liquids,
4) a spray gun with an appropriately-sized nozzle, (or a spray bar and a multiplicity of nozzles) and
5) necessary tubing, fittings, connections, control buttons, a box to enclose the apparatus, as well as a pressure relief valve and/or bypass valve, freeze protection, a particulate-filtering screen or screens, a solenoid to prevent non-pumped release of the release coating as optional ancillary devices.
Examples of the carbonator pumps utilized in the instant invention include, but are not limited to, vane-type positive-displacement pumps by PROCON Products, a division of Roehlen Industries, in Murfreesboro, Tenn. Typically, a Series 1, up to potentially a Series 6 type of pump can be used. Other pumps capable of producing a minimum of approximately 1 GPM at 250-300 psi could conceivably work, but this kind of pump has high reliability and durability, and has the added advantage of not being overly expensive, and so it is the preferred embodiment.
An example of the type of relay that is useful in the instant invention include, but is not limited to, a JCK-24 type of relay by the Square D Company, which utilizes a momentary contact input to start an adjustable timed relay, with the timing range adjustable from about 2 seconds to about 1.5 minutes. The relay is capable of operating up to a 10-amp inductive load. Time length adjustment is made by turning a knob on the relay, and the relay fits into a base, making field replacement of the relay relatively easy.
Another example of the type of relay that finds utility in the instant invention is a CT-2-A20/M time cube relay system by Turck Inc., of Minneapolis, Minn. This is also a multi-component system, having a base, a separate timing mechanism, and the actual relay that controls the load is in a third module, which is relatively inexpensive and easily field replaceable.
Those skilled in the art will recognize that other timing relays and/or relay combinations would work, but they must be able to start and run a motor sized large enough to drive the desired pump. The major minimum requirements of the relay are that it have a reproducible timing range which includes the timeframe of 1-2 minutes minimum, the capability to start and run an appropriately-sized motor, on the order of ⅓ horse power minimum, be robust, easily field-replaceable, and relatively inexpensive.
An example of the induction/injection valve with a high induction capacity includes, but is not limited to, a xe2x80x9cC Seriesxe2x80x9d injector by Dema Engineering Company, of Saint Louis, Mo. In a preferred embodiment, a typical such injector might be a 200CS brass injector, fitted with a stainless-steel high-induction kit. This injector valve has the capacity to inject as much as about 0.1 gallon concentrate per gallon of water flow at about 200 psi. Other injector valves may also fulfill the requirements of the instant invention, but these are the preferred embodiment.
An example of a solenoid valve that finds utility in the instant invention is a xe2x85x9cxe2x80x3 normally-closed, 110V solenoid valve manufactured by the Automatic Switch Company, with a required differential operating pressure range of 5-300 psi. Other similar solenoid valves may also fulfill the requirements of the instant invention, but this kind is a preferred embodiment.
An example of the spray gun and appropriately-sized nozzle is an Admiral Pump 1000 industrial spray gun, with a TP 6505 LP nozzle and associated hardware. This combination gives a good spray pattern with the above pump/injector valve, without causing undue back pressure. Other nozzle/spray gun combinations are effective in this invention, and one skilled in the art will realize that each combination of pump, injector, solenoid valve, etc. will require some potential adjustments in the nozzle selection.
In another embodiment, it may be advantageous to combine one or more to make an apparatus that can spray through multiple nozzles at once, so as to more rapidly coat a truck bed, for example.